In this project, an investigation on the combined application of water-in-fuel emulsion (WFE) and exhaust gas recirculation (EGR) in a medium speed common rail, 4-stroke diesel engine at the Large Engine Research Facility (LERF) at PSI has been performed in order to achieve low NOx and soot emissions.
Within the projects CCEM “Low-NOx” and Hercules-2 (Horizon 2020), the test engine has been modified to operate with a semi-short route EGR configuration and the TC-system has been re-matched in order to operate over the entire load range. An advanced fuel consumption measurement and WFE equipment was successfully applied.
In the framework of this project, a measurement campaign has been conducted, which includes parameter variation such as water content (up to 10 wt%), rail pressure and start of injection timing. The measurement campaign is accompanied the analysis of engine performance data via a 0-D simulation tool (GT-Power) to analyse the heat release behaviour. Furthermore, the gaseous emissions and soot have been characterized.
Applying low content water-in-fuel emulsion (up to 10wt%) reduce the soot emission up to 85% with the according injection pressure and start of injection time tuning. The engine efficiency has been observed to slightly increase up to 0.85%. Furthermore, the NOx emission was slightly reduced with WFE operation. Only the rather quick damage of injector components show a drawback and additional measures regarding material and design would be needed.
The results of the combined application of EGR and WFE in a medium speed diesel engine give a more detailed insight into the applicability of these two technologies to meet the emission legislations for NOx (IMO TIER) and the simultaneous abatement of soot.
